Seasonal changes in soil water repellency of different land use types in Inner Mongolia grassland

Abstract

Soil water repellency (SWR) is a physical phenomenon in which the rate of wetting is restricted and water beads are formed on the soil surface where the soil is called water-repellent soil. SWR analysis is necessary to interpret nonuniform wetting and preferential flow for site-specific ecosystems. This study aims to investigate the effects of soil water conditions and land use types on SWR in Leymus chinensis steppe soil in Xilinhot, Inner Mongolia, China. The main objective is to determine how SWR in soils in Inner Mongolia is influenced by different grassland utilization types, including no grazing since 1979 and 1999, winter grazing, and continuous grazing, by using water drop penetration time (WDPT). Results show that a slightly hydrophobic or hydrophilic soil behavior was often observed, and SWR was most evident in the months with the highest evaporation despite heavy rainfall. Changes in SWR in different seasons were affected by grazing intensity. The highest number of hydrophobic soil samples was found in the continuous grazing sites, followed by that in the winter grazing sites. Few hydrophobic soil samples were detected in the ungrazed sites since 1979, and the lowest number of samples was observed in the ungrazed sites since 1999. The SWR of different particle size classes decreased with increasing particle size. Therefore, SWR was significantly correlated with soil particle size class at 0–0.05 and 0.05–0.1mm. These results emphasized the need to consider SWR in soil utilization because grazing intensity affects the soil repellent properties in steppe soil and provided a basis for the development of grassland management.